Control Channel and Data Channel Design for User Equipment

ABSTRACT

Control channel and data channel design for LTE user equipments are proposed. Due to reduced bandwidth design for cost reduction, resources for UEs are limited to contiguous six physical resource block (PRB) pairs (1.4 MHz). Six or less contiguous PRBs per narrow sub-band located in the whole channel bandwidth is allocated for transmission and reception for UEs. Novel control channel and data channel designs are proposed to make UEs be able to camp on LTE cells. In one embodiment, control channel configuration information is provided to UE. The control channel occupies one or more subframes within the allocated resources. The control channel configuration information comprises a number of aggregation level, a number of repetition, and a number of blind decoding trials.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 from U.S.Provisional Application No. 62/108,640, entitled “The Methods to SupportLTE UEs with Bandwidth Reduction,” filed on Jan. 28, 2015, the subjectmatter of which is incorporated herein by reference.

TECHNICAL FIELD

The disclosed embodiments relate generally to LTE networks, and, moreparticularly, to channel design and measurement for LTE user equipments(UEs).

BACKGROUND

Machine-Type Communication (MTC) is an important revenue stream foroperators and has a huge potential from the operator perspective.Lowering the cost of MTC user equipment (UEs)/devices is an importantenabler for the implementation of the concept of “Internet of Things”(IOT). Many MTC devices are targeting low-end (low average revenue peruser, low data rate) applications that can be handled adequately byGSM/GPRS. Owing to the low-cost of these devices and good coverage ofGSM/GPRS, there is very little motivation for MTC UE suppliers to usemodules supporting the LTE radio interface. In order to ensure thatthere is a clear business benefit to MTC UE vendors and operators formigrating low-end MTC devices from GSM/GPRS to LTE networks, a new typeof terminal, i.e. a low cost (LC) MTC UE, is introduced in Rel-11. Thecost of the LC-MTC UEs is tailored for the low-end of the MTC market tobe competitive with that of GSM/GPRS terminals. The LC-MTC UEs arecharacterized by: 1) One Rx antenna; 2) Downlink and uplink maximum TBSsize of 1000 bits; 3) Bandwidth reduction (BR)—resources for eachchannel transmission are limited to contiguous 6 PRBs (1.4 MHz) for costreduction, and 4) Coverage enhancement—some applications of LC-MTC UEswill require 15-20 dB coverage extension and repeated transmission is acommon technique to compensate penetration losses.

In LTE Rel. 12, it is shown that the implementation of half-duplex FDD(HD-FDD) MTC with single received antenna is cost-competitive. Thebandwidth reduction technique can offer further cost reduction. The UEwith bandwidth reduction (BR-UE) can be implemented with lower cost byreducing the buffer size, clock rate for signal processing, and so on.However, it also faces many challenges when the BR-UE tries to camp onthe LTE cell of which cell bandwidth is larger than the supportedbandwidth of its bandwidth. In LTE, the control channels includingPCFICH, PHICH and PDCCH span over whole bandwidth. When the supportedbandwidth at the BR-UE is less than cell bandwidth indicated by PBCH,the BR-UE is only capable of decoding PBCH and PSS/SSS allocated incenter 6 PRB pairs. The BR-UE is not able to decode SIBs, PDSCH, RAR, orPaging due to lack of ability of decoding control channels. Novelcontrol channel designs are needed to make the BR-UE be able to camp onthe LTE cell.

When there are too many BR-UEs, it is impossible for the serving eNodeBto schedule all BR-UEs at center 6 PRB pairs. Consequently, the servingeNodeB may try to schedule different BR-UEs at different PRB pairs. Inthese cases, the BR-UE that is not scheduled at the center 6 PRB pairsis unable to perform intra-frequency measurement for handover andReference Signal Time Difference (RSTD) measurement. Therefore, methodsfor intra-frequency/RSTD measurement are needed.

Moreover, the BR-UE cannot offer the channel quality report of wholedownlink (DL) cell bandwidth. The BR-UE cannot measure the wideband CQIat single subframe. Therefore, methods to assess the whole bandwidth areneeded such that the serving eNodeB can schedule BR-UEs in efficientmanner.

SUMMARY

Methods to support LTE user equipments with bandwidth reduction areproposed. Due to reduced bandwidth design for cost reduction, resourcesfor UEs are limited to contiguous six physical resource block (PRB)pairs (1.4 MHz). Six or less contiguous PRBs per narrow sub-band locatedin the whole channel bandwidth is allocated for transmission andreception for UE. Novel control channel and data channel designs areproposed to make UEs be able to camp on LTE cells. Methods forintra-frequency measurement, for received signal time difference (RSTD)measurement, and for channel quality assessment for UEs are alsoprovided.

In one embodiment, a serving base station configures a CE mode for auser equipment (UE) in a mobile communication network. The base stationallocates a set of resources to the UE. The set of resources belongs toa narrow subband in a wider channel bandwidth. The narrow subbandcomprises a plurality of contiguous PRB pairs including a controlchannel and a data channel. The base station provides the controlchannel configuration information to the UE. The control channeloccupies over one or more subframes within the set of resources. Thecontrol channel configuration information comprises a number ofaggregation level, a number of repetition, and a number of blinddecoding trials. In one example, the base station assigns a measurementgap for intra-frequency and RSTD measurements. In another example, thebase station configures frequency hopping for the UE and indicates PRBpair starting index per subframe for channel state information (CSI)measurements.

In another embodiment, a user equipment (UE) configures a CE mode in amobile communication network. The UE determines a set of resourcesallocated to the UE. The set of resources belongs to a narrow subband ina wider channel bandwidth. The narrow subband comprises a plurality ofcontiguous PRB pairs including a control channel and a data channel. TheUE obtains the control channel configuration information. The controlchannel occupies over one or more subframes within the set of resources.The control channel configuration information comprises a number ofaggregation level, a number of repetition, and a number of blinddecoding trials. In one example, the UE is assigned a measurement gapfor intra-frequency and RSTD measurements. In another example, the UE isconfigured with frequency hopping and receives PRB pair starting indexper subframe for channel state information (CSI) measurements.

In one embodiment, a base station allocates a first set of resources toa UE in a mobile communication network. The first set of resourcesbelongs to a first narrowband in a wider channel bandwidth. The firstnarrowband comprises a plurality of contiguous PRB pairs over a firstperiod. The base station allocates a second set of resources to the UE.The second set of resources belongs to a second narrowband comprising aplurality of contiguous PRB pairs over a second period. The base stationassigns a measurement gap between the first and the second periods forintra-frequency and RSTD measurements for the UE. In one example, thebase station configures a frequency-hopping pattern for the UE andindicates PRB pair starting index per subframe for CSI measurements.

In another embodiment, a UE obtains a first set of resources in a mobilecommunication network. The first set of resources belongs to a firstnarrowband in a wider channel bandwidth. The first narrowband comprisesa plurality of contiguous PRB pairs over a first period. The UE obtainsa second set of resources belongs to a second narrowband comprising aplurality of contiguous PRB pairs over a second period. The UE performsintra-frequency and RSTD measurements based on an assigned measurementgap between the first and the second periods. In one example, the UE isconfigured with frequency hopping and receives PRB pair starting indexper subframe for channel state information (CSI) measurements.

Other embodiments and advantages are described in the detaileddescription below. This summary does not purport to define theinvention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like numerals indicate like components,illustrate embodiments of the invention.

FIG. 1 illustrates a mobile communication network 100 with BR-UEs inaccordance with embodiments of the current invention.

FIG. 2 illustrates control channel and data channel design for BR-UEs inaccordance with one novel aspect.

FIG. 3 illustrates a message sequence chart of resource allocation andconfiguring control and data channels for a BR-UE.

FIG. 4 illustrates one alternative embodiment of control channel anddata channel designs for BR-UEs in accordance with one novel aspect.

FIG. 5 illustrates another alternative embodiment of control channel anddata channel designs for BR-UEs in accordance with one novel aspect.

FIG. 6 illustrates a first embodiment of BR-control channel and PDCCHdesign for BR-UEs.

FIG. 7 illustrates a second embodiment of BR-control channel and PDCCHdesign for BR-UEs.

FIG. 8 illustrates different examples of PDCCH design with differentaggregation levels for BR-UEs.

FIG. 9 illustrates one embodiment of assigning measurement gap forintra-frequency/RSTD measurements for BR-UEs.

FIG. 10 illustrates one embodiment of assigning frequency-hoppingpattern for performing scanning and narrowband CQI measurements andreporting.

FIG. 11 is a flow chart of a method of control channel and data channeldesign from eNB perspective in accordance with one novel aspect.

FIG. 12 is a flow chart of a method of control channel and data channeldesign from UE perspective in accordance with one novel aspect.

FIG. 13 is a flow chart of a method of intra-frequency and RSTDmeasurements from eNB perspective in accordance with one novel aspect.

FIG. 14 is a flow chart of a method of intra-frequency and RSTDmeasurements from UE perspective in accordance with one novel aspect.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

Machine type communication is a form of data communication that involvesone or more entities that do not necessarily need human interaction. Aservice optimized for machine type communication differs from a serviceoptimized for human-to-human (H2H) communication. Typically, MTCservices are different to current mobile network communication servicesbecause MTC services involve different market scenarios, pure datacommunication, lower cost and effort, and a potentially very largenumber of communicating terminals with little traffic per terminal.Therefore, it is important to distinguish low cost (LC) MTC from regularUEs. UE with bandwidth reduction (BR-UE) can be implemented with lowercost by reducing the buffer size, clock rate for signal processing, andso on. However, it also faces many challenges when BR-UE tries to campon the LTE cell of which cell bandwidth is larger than the supportedbandwidth of its bandwidth. Further, BR-UE that is not scheduled atcenter 6 PRB pairs is unable to perform intra-frequency measurement forhandover and Reference Signal Time Difference (RSTD) measurement.Moreover, BR-UE cannot offer the channel quality report of wholedownlink (DL) cell bandwidth. Apparatus and methods are thus providedand described below in details to support LTE UEs with bandwidthreduction.

FIG. 1 illustrates a mobile communication network 100 with BR-UEs inaccordance with embodiments of the current invention. Wirelesscommunication system 100 includes one or more fixed base infrastructureunits forming a network distributed over a geographical region. The baseunit may also be referred to as an access point, an access terminal, abase station, a Node-B, an eNode-B (eNB), or by other terminology usedin the art. In FIG. 1, the one or more base stations 101 and 102 serve anumber of MTC UEs 103 and 104 within a serving area, for example, a cellor a cell sector. In one embodiment, MTC UEs 103 and/or 104 are regularUEs that are configured to be MTC UEs. In another embodiment, regularUEs can be configured to be BR-UEs. A BR-UE can be configured from aregular UE, an MTC UE or any other type of UE. The BR-UE can beconfigured locally on the UE or dynamically configured through networksignaling. In some systems, one or more base stations are communicablycoupled to a controller forming an access network that is communicablycoupled to one or more core networks. The disclosure, however, is notintended to be limited to any particular wireless communication system.

Generally, serving base stations 101 and 102 transmit downlinkcommunication signals 112 and 113 to MTC UEs in the time and/orfrequency domain. MTC UEs 103 and 104 communicate with one or more basestations 101 and 102 via uplink communication signals 111 and 114. UE orthe mobile station may also be referred to as a mobile phone, laptop,and mobile workstation and so on. In FIG. 1, the mobile communicationnetwork 100 is an OFDM/OFDMA system comprising a base station eNB 101eNB 102 and a plurality of BR-UE 103 and BR-UE 104. When there is adownlink packet to be sent from the eNB to the BR-UE, each BR-UE gets adownlink assignment, e.g., a set of radio resources in a physicaldownlink shared channel (PDSCH). When a BR-UE needs to send a packet toeNB in the uplink, the BR-UE gets a grant from the eNB that assigns aphysical downlink uplink shared channel (PUSCH) consisting of a set ofuplink radio resources. The BR-UE gets the downlink or uplink schedulinginformation from a physical downlink control channel (PDCCH) or anenhanced PDCCU (ePDCCH) that is targeted specifically to that BR-UE. Thedownlink or uplink scheduling information and the other controlinformation, carried by PDCCH/ePDCCH, is referred to as downlink controlinformation (DCI).

FIG. 1 also shows an exemplary diagram of protocol stacks forcontrol-plane for BR-UE 103 and eNB 101. BR-UE 103 has a protocol stack121, which includes the physical (PHY) layer, the medium access control(MAC) layer, the radio link control (RLC) layer, the pack dataconvergence protocol (PDCP) layer, and the radio resource control (RRC)layer. Similarly, base station eNB 101 has a protocol stack 122, whichincludes the PHY layer, the MAC layer, the RLC layer, the PDCP layer,and the RRC layer, each of which connects with their correspondingprotocol stack of BR-UE protocol stack 121.

FIG. 1 further illustrates simplified block diagrams for BR-UE 103 andeNB 101, respectively. BR-UE 103 has an antenna 135, which transmits andreceives radio signals. A RF transceiver module 133, coupled with theantenna, receives RF signals from antenna 135, converts them to basebandsignals and sends them to processor 132. RF transceiver 133 alsoconverts received baseband signals from processor 132, converts them toRF signals, and sends out to antenna 135. Processor 132 processes thereceived baseband signals and invokes different functional modules toperform features in BR-UE 103. Memory 131 stores program instructionsand data 134 to control the operations of BR-UE 103. BR-UE 103 alsoincludes multiple function modules that are circuits to be implementedand configured to carry out different tasks in accordance withembodiments of the current invention. A resource configuration module141 acquires resource allocation information, either from predefinedrules, from higher layer messaging, from physical layer signaling, orany combination thereof, and determines the allocated resources fordownlink reception and uplink transmission. A frequency-hopping module142 receives frequency-hopping information from the base station anddetermines frequency hopping at different subframes for coverageextension. A decoder 143 performs blind decoding of allocated controland data channels. A measurement module 144 performs intra-frequencymeasurement for handover and Reference Signal Time Difference (RSTD)measurement, as well as channel state information (CSI) measurement withnarrowband channel quality indicator (CQI) to support wideband CQI.

Also shown in FIG. 1 is an exemplary block diagram for eNB 101. eNB 101has an antenna 155, which transmits and receives radio signals. A RFtransceiver module 153, coupled with the antenna, receives RF signalsfrom antenna 155, converts them to baseband signals, and sends them toprocessor 152. RF transceiver 153 also converts received basebandsignals from processor 152, converts them to RF signals, and sends outto antenna 155. Processor 152 processes the received baseband signalsand invokes different functional modules to perform features in eNB 101.Memory 151 stores program instructions and data 154 to control theoperations of eNB 101. eNB 101 also includes function modules that carryout different tasks in accordance with embodiments of the currentinvention. A resource allocation module 156 performs resource allocationfunctions to support the BR-UE with reduced overhead and improved systemperformance. A scheduler 157 schedules uplink transmission and downlinkreception for the BR-UE based on the allocated resources. Aconfiguration module 158 assigns frequency hopping patterns andmeasurement gaps for the BR-UE to enable frequency diversity gain andmeasurements functionalities.

FIG. 2 illustrates control channel and data channel designs for BR-UEsin accordance with one novel aspect. Due to reduced bandwidth design forcost reduction, resources for BR-UEs are limited to contiguous sixphysical resource block (PRB) pairs (1.4 MHz). Six or less contiguousPRBs per MTC narrow sub-band located in the whole channel bandwidth isallocated for transmission and reception, as depicted by box 201 of FIG.2. However, such bandwidth reduction introduces the following problems.First, legacy control channels including PCFICH, PHICH, and PDCCH spanover whole bandwidth such that BR-UE cannot hear the legacy controlchannel. It also means the BR-UEs are unable to receive data scheduledby legacy control channel. Second, the BR-UE can only receive the signalwithin x consecutive PRB pairs. The eNB may (dynamically) schedule theDL signal on different PRB pairs on subframe basis to support massiveMTC devices. If there is no signal or predefined rules to make sure eNBand BR-UE know how to transmit and receive DL signal, the BR-UE will notbe capable of receiving any signal from eNB. Even if the PRB pairs areknown for both BR-UE and eNB, new control channel and data channel forBR-UE are necessary. Third, the first OFDM symbols of each subframe areoccupied by legacy control channel but this information is not availablefor BR-UEs. As a result, BR-UE may have incorrect rate matchingbehavior. Fourth, For BR-UEs, the control channel is unreliable due tolack of frequency diversity. Consequently, the cell coverage shrinks andthe BR-UE is likely in the coverage hole.

In accordance with one novel aspect, the proposed BR-PCFICH, BR-PDCCH,BR-PHICH, BR-control channel and BR-PDSCH for BR-UEs are designed withthe following rules. To make sure that the BR-UE will listen to the PRBspairs that the eNB may schedule all its DL channels on, the followingparameters in every subframe shall be available at both the eNB side andthe BR-UE side. Starting PRB index: it can be obtained by any ofcell-specific predefined rules, UE-specific predefined rules, higherlayer signaling on previous subframe(s), and new designed DCI onprevious subframes(s). Number of consecutive PRB pairs that can are usedto schedule DL signal for this BR-UE denotes as y: y can be a predefinedvalue or from higher layer signaling on previous subframe(s) and newdesigned DCI on previous subframes(s). To successfully decode all DLchannel, y shall be less than or equal to x.

Note that BR-PRB pairs are defined as the set of PRB pairs from PRB pairstarting index to PRB pair starting index+y-1 that are used to scheduleDL signal for this BR-UE. The PRB allocation of BR-PRB pairs can bechanged on subframe basis. The PRB allocation of BR-PRB pairs can bedecided according to predefined rules, random access response, DCIorder, and higher layer signaling. With the knowledge of the location ofthe BR-PRB pairs, the BR-UE can decode all DL channels within the BR-PRBpairs. All DL channels within the BR-PRB pairs include control channel(BR-control channel) and data channel (BR-PDSCH). NACK/ACK of UL datatransmission and information of BR-PDSCH decoding (e.g. RElocation/modulation order/information size/transmissionmode/corresponding reference signal/ . . . of BR-PDSCH) are carried inBR-control channel. The BR-control can be implemented by at least one ofBR-PHICH, BR-PCFICH and BR-(e)PDCCH for BR-UE.

Within the BR-PRB pairs, BR-PCFICH is used to carry parameters to decodeother BR-control channels and/or date channels for BR-UEs. BR-PHICH isused to indicate AC/NACK of UL data transmission for BR-UEs. BothBR-PCFICH and BR-PHICH can be distributed on several OFDM symbols orlocalized at one or several OFDM symbols within the PRB pairs. BR-PCFICHregion within the PRB pairs can be known by BR-UEs by predefined rulesand/or higher layer signaling. BR-PHICH region within the PRB pairs canbe known by BR-UEs by predefined rules, BR-PCFICH, and higher layersignaling.

BR-(e)PDCCH within the BR-PRB pairs over one or several subframe can beused to carry higher layer command(s) and/or some information in DL datadecoding for BR-UEs. The information in DL data decoding for BR-UEs canbe at least one of: legacy control region size, RE locations, modulationorder, information size, transmission mode, corresponding referencesignal of BR-PDSCH, enable or disable of BR-PDSCH repetition, therepetition level and the starting subframe index of BR-PDSCH repetitionis signaled. BR-(e)PDCCH within the BR-PRB pairs can be distributed,span at one or several OFDM symbol(s) or span one or several PRB pairs.BR-(e)PDCCH region within the BR-PRB pairs over one or several subframecan be obtained according to at least one of predefined rule, BR-PCFICHand higher layer signaling. The hypotheses of blind detection ofBR-(e)PDCCH can be controlled according to at least one of predefinedrule, BR-PCFICH and higher layer signaling. The BR-UEs can be requestedto skip monitoring some subframes with new data transmission ifconfigured by higher signaling. For example, to simplify decoding flow,BR-UE can skip monitoring the subframes with CSI-RS/ZP CSI-RS/NZPCSI-RS. Moreover, the active ratio is reduced and it is helpful to savemore power.

BR-PDSCH within the BR-PRB pairs is used to carry higher layersignaling/data for BR-UEs. DL data can beUE-specific/Cell-specific/BR-UE specific for the particular group ofBR-UEs (multicast). BR-PDSCH within the BR-PRB pairs is not overlappedwith BR-control channel. BR-PDSCH within the BR-PRB pairs over one orseveral subframes can be obtained according to at least of thepredefined rule(s), other BR-control channel(s) within the BR-PRB pairsover one or several subframes, and higher layer signaling. Theinformation of BR-PDSCH decoding within the BR-PRB pairs can be obtainedaccording to at least one of the predefined rule(s), BR-controlchannel(s) within the BR-PRB pairs over one or several subframe andhigher layer signaling. To improve the quality of channel estimation,the pilots for BR-PDSCH decoding can be cell common pilots and/or BR-UEcommon/specific pilots.

FIG. 3 illustrates a message sequence chart of resource allocation andconfiguring control and data channels for a BR-UE. In step 311, aserving eNB 301 configures a communication equipment (CE) mode for aBR-UE 302. Two CE modes are defined for RRC_Connected UEs. CE Mode Adescribes a set of behaviors for no repetitions and small number ofrepetitions. CE Mode B describes a set of behaviors for large number ofrepetitions. For each physical channel, there may be some common numberof repetitions that can be used in CE Mode A and CE Mode B. The CE modescan have additional association with DCI formats, CSI feedback, etc. Instep 312, eNB 301 allocates a set of resources that belongs to a narrowsub-band in a wider channel bandwidth to BR-UE 302. The narrow sub-bandcomprises a plurality of contiguous physical resource blocks (PRBs)including a control channel and a data channel for the BR-UE. Forexample, the starting PRB index and the number of consecutive PRB pairsare provided to BR-UE 302 via predefined rule and high layer signaling.In addition, eNB 301 configures BR-control channel within the allocatednarrow sub-band for BR-UE 302. In one example, the control channelconfiguration information comprises a number of aggregation level, anumber of repetition, and a number of blind decoding trials of thecontrol channel. In step 313, eNB 301 transmits DL signals to UE 302,which includes both control channel and data channel. In step 321, UE302 decodes the control channel and data channel within the allocatednarrow sub-band based on the control channel configuration information.

BR-UE must be able to coexist with legacy LTE UE. The legacy CFI valueis carried by PCFICH but BR-UEs are not able to decode PCFICH. Ifmissing legacy CFI value, the rate matching behavior of all DLBR-channel could be incorrect. One solution is to indicate the startingOFDM index of BR-PDSCH in semi-static manner. The semi-static startingOFDM symbol can be from higher layer signaling or predefined value. Forexample, eNB can change legacy CFI value on subframe basis such thatsemi-static starting OFDM index of BR-PDSCH value must be larger than orequal to the maximum legacy control region to prevent incorrect datachannel rate matching. However, configuring semi-static starting OFDMsymbol of BR-PDSCH may waste some OFDM symbol resources. On the otherhand, if the legacy CFI is also carried in BR-control channel, there isno wasted OFDM symbol. For example, the legacy CFI can be carried inBR-PCFICH or BR-(e)PDCCH.

FIG. 4 illustrates one alternative embodiment of control channel anddata channel designs for BR-UEs in accordance with one novel aspect. Theexample of BR-control channel and BR-PDSCH provides a solution to legacyCFI issue.

FIG. 5 illustrates another alternative embodiment of control channel anddata channel designs for BR-UEs in accordance with one novel aspect. Theexample of BR-control channel and BR-PDSCH provides a solution to legacyCFI issue.

FIG. 6 illustrates a first embodiment of BR-control channel and ePDCCHdesign for BR-UEs. For reliable BR-control channel, in the firstembodiment, the maximum aggregation level can be enlarged with crosssubframe scheduling. To simplify blind decoding flow, the maximumaggregation level can be signaled by BR-PCFICH. As depicted by FIG. 6,one subframe 601 is consumed by BR-control in every HARQ retransmission.It requires longer active time, which results in higher powerconsumption for UE and lower spectrum efficiency. The UE can adopt lowercode rate for BR-PDSCH by increasing repetition level and loweringtransport block size (TBS) such as TDD/MCS-1 in data channel.

FIG. 7 illustrates a second embodiment of BR-control channel and ePDCCHdesign for BR-UEs. For reliable BR-control channel, in the secondembodiment, eNB repeats the whole BR-control channels in severalsubframes. To simplify the complexity on decoding of BR-channels, thestarting subframe index of repetition (e.g. subframe 701) is known by atleast one of predefined rule(s), configured by RAR and higher layersignaling. With the knowledge of the starting subframe index ofrepetition, the needed memory to decoding all BR-control channels andBR-data channel will not increase. The main reason to enable repetitionis that the channel quality for this BR-UE is quite poor. Repetitionnumber can be decided in increasing or decreasing manner. For example,in increasing manner, the repetition mechanism can be triggered by BR-UEreporting or by conditions. In one example, the repetition mechanism istriggered if the aggregation level of BR-(e)PDCCH is larger than athreshold and if eNB still cannot get any ACK/NACK from the target BR-UEfor a predefined attempt number (N1). If the repetition mechanism istriggered and if eNB still cannot get any ACK/NACK from the target BR-UEfor the predefined attempt number (N2), then the repetition level isdoubled. If the repetition level is larger than the threshold (N3), thenthe BR-UE can be treated as out of service coverage. On the other hand,if the repetition mechanism is triggered and if eNB still can get everyACK/NACK from the target BR-UE for the predefined attempt number (N4),then the repetition level is halved. If repetition level is equal toone, then the repetition mechanism is disabled.

For reliable BR-control channel, the first embodiment and the secondembodiment can be combined. Repetition level can be carried by new DCIor obtained blind detection. However, for the NACK/ACK reporting ofBR-PDSCH, the resource of NACK/ACK allocation can be controlled by atleast one of DCI carried by BR-control, higher layer signaling andpredefined rules.

Furthermore, dynamic resource allocation for BR-control channel can beadopted for spectrum efficiency. For example, for the BR-UE close tocell center, the channel quality is quite well such and there is no needto allocate that many resources for BR-control channel. In a firstoption, Support dynamic resource allocation for BR-control channels viaBR-PCFICH. It can also reduce the blind detection complexity by bundlingBR-PCFICH and blind detection number for each aggregation level. In asecond option, limited possible sizes of BR-control channel+blinddetection the BR-control size by BR-UE. For example, there are fourpossible BR-(e)PDCCH channel sizes. In each possible BR-(e)PDCCHchannel, the possible aggregation(s) and candidate number are limitedfor complexity reduction. In a third option, there is one BR-controlchannel size and pre-allocate resource for BR-control channels. If theresource is not used by BR-control channel, it can be released forBR-PDSCH transmission.

FIG. 8 illustrates different examples of PDCCH design with differentaggregation levels for BR-UEs. The PDCCH candidates are defined based onthe physical structure of resource element group (REG) and controlchannel element (CCE), and each candidate PDCCH has its own aggregationlevel utilizing CCE as the basic unit. Within the radio resources forPDCCH candidate definition, PRB pairs are first partitioned into REGs,and then each CCE is composed of several REGs. PDCCH aggregation levelcan be 1-16 CCEs depending on the PDCCH design. FIG. 8 illustrates fivepossible aggregation levels: 1/2/4/8/16. In one example aggregationlevel=16CCE, 19 CCE can be used for BR-control channels: 16 CCE forBR-PDCCH, 2 CCE for BR-PCFICH, 1 CCE for BR-PHICH.

There could be many BR-UEs within the coverage of an eNB. When there aretoo many BR-UEs, it is impossible to schedule all BR-UEs at center 6 PRBpairs, which carries PBCH and PSS/SSS for cell identification. Dependingupon scheduling algorithm of the eNB, it is possible that the BR-UE isscheduled at the fixed PRB pairs that excludes center 6 PRB pairs for awhile. In the worst case, there is no subframe for intra-frequencymeasurement, and for reference signal time different (RSTD) measurement.Therefore, it is proposed to make BR-UEs be able to performintra-frequency/RSTD measurement.

Intra-frequency measurement includes RSRP/RSRQ measurements of theserving cell and neighboring cells. RSRP/RSRQ measurements are used todecide whether handover procedure shall be triggered. RSTD measurementsis for positioning purpose. RSTD is a measure of time difference ofarrival signals from different eNBs. The time differences from differentbase stations are then used to drive distance differences, which arefurther used to estimate UE position if having many RSTD measurements(e.g., with many different eNBs).

FIG. 9 illustrates one embodiment of assigning measurement gap forintra-frequency/RSTD measurements for BR-UEs. For intra-frequency/RSTDmeasurement, the BR-UE shall have enough DL subframes that can be usedfor cell identification and measurement. In the embodiment of FIG. 9,the eNB assigns the frequency-hopping pattern that indicates PRB pairstarting index per subframe for the BR-UE. Based on thefrequency-hopping pattern, the BR-UE knows which DL subframes can beused for intra-frequency/RSTD measurement and the eNB guarantees thatthere are enough DL subframes can be used for intra-frequency/RSTDmeasurement. As depicted by box 900, the wideband DL BW is 50 PRBs. ForBR-UEs, the periodicity of frequency hopping is 40 ms. During every 40ms, 10 ms is available for DL data reception and intra-frequency andRSTD measurement (e.g., center PRBs allocated), and the remaining(30−2*RF returning time)ms is available for DL data reception only.

In another embodiment, the eNB assigns a period of time forintra-frequency/RSTD measurement for the BR-UE. The BR-UE can skip someDL data receptions/monitoring and perform intra-frequency/RSTDmeasurement during the period of time (e.g., measurement gap) assignedby the eNB. The measurement gaps are used to enable the BR-UE to retuneto central six PRBs to perform intra-frequency measurements. Themeasurement gap can be continuous or discontinuous. The configurationfor measurement gap can be periodic or aperiodic. From BR-UEperspective, during the measurement gap assigned by the eNB, the BR-UEtunes the passband of DL filter for intra-frequency/RSTD measurement,and skips BR-PDCCH monitoring.

A BR-UE can only access of partial cell bandwidth at one subframe.Therefore, the BR-UE must have the information on which PRB pairs theserving eNB will schedule data. For the serving eNB without theinformation of UE channel quality of whole band, it is difficult toenable dynamic scheduling to allocate data on different PRB pairs. Forlow mobility BR-UE, if eNB has the whole band channel quality, eNB canassign a fixed/semi-static frequency-hopping pattern.

In accordance with one novel aspect, to collect of channel qualities ofwhole DL BW at the BR-UE side, channel scan procedure may be necessaryto estimate channel quality in the whole DL BW. Beforeaperiodic/periodic (BR-subband) CQI reporting/frequency hopping pattern(re)assignment, the BR-UE can report DL channel quality by channel scanprocedure to help eNB to make decision. BR-subband RSRP and BR-subbandRSRQ is long-term averaged measures and BR-subband CQI is a short-termaveraged measure. Based on the purpose of channel scan, eNB canconfigure the trigger or measure quantity as at least one of BR-subbandRSRP, BR-subband RSRQ, and BR-subband CQI. Further, eNB can configurethe reporting quantity as at least one of BR-subband RSRP, BR-subbandRSRQ and BR-subband CQI. In one embodiment, eNB can assign thefrequency-hopping pattern that indicates PRB pair starting index persubframe for the BR-UE. With the frequency-hopping pattern, the BR-UEexactly knows which PRB pairs shall be scanned and assessed in everysubframe.

FIG. 10 illustrates one embodiment of assigning frequency-hoppingpattern for performing scanning and narrowband CQI measurements andreporting. In step 1011, eNB 1001 assigns the BR-UE specific/cellspecific frequency hopping pattern, which indicates BR-PRB pairs persubframe for the BR-UE 1002. With this configured frequency hoppingpattern, BR-UE 1002 can perform channel-scanning procedure in step 1012.Based on the frequency-hopping pattern, BR-UE 1002 knows which PRB pairsshall be estimated for channel quality and reported. The CSI measurementis performed for narrowband used for BR-PDCCH monitoring. During thechannel scanning procedure, the eNB can still transmit DL data on thePRB pairs that the BR-UE is monitoring, or the eNB can buffer DL datafor this BR-UE. During the channel scanning procedure, BR-UE 1002 canskip UL transmission. In step 1013, BR-UE 1002 reports the narrowbandCQI based on the predefined rule or DCI order. In addition, eNB 1001 canconfigure the trigger, measure, or reporting quantity as at least one ofBR-subband RSRP, BR-subband RSRQ, and BR-subband CQI. In step 1014, eNB1001 changes an appropriate frequency-hopping pattern for BR-UE 1002after receiving the CQI reporting. Note that wideband CQI is obtainedusing all the narrowband used for BR-PDCCH monitoring. Wideband CQI isthe same as narrowband CQI when the BR-PDCCH is not configured withfrequency hopping.

FIG. 11 is a flow chart of a method of control channel and data channeldesign from eNB perspective in accordance with one novel aspect. In step1101, a serving base station configures a CE mode for a user equipment(UE) in a mobile communication network. In step 1102, the base stationallocates a set of resources to the UE. The set of resources belongs toa narrow subband in a wider channel bandwidth. The narrow subbandcomprises a plurality of contiguous PRB pairs including a controlchannel and a data channel. In step 1103, the base station provides thecontrol channel configuration information to the UE. The control channeloccupies over one or more subframes within the set of resources. Thecontrol channel configuration information comprises a number ofaggregation level, a number of repetition, and a number of blinddecoding trials. In one example, the base station assigns a measurementgap for intra-frequency and reference signal time difference (RSTD)measurements. In another example, the base station configures frequencyhopping for the UE and indicates PRB pair starting index per subframefor channel state information (CSI) measurements.

FIG. 12 is a flow chart of a method of control channel and data channeldesign for from UE perspective in accordance with one novel aspect. Instep 1201, a user equipment (UE) configures a CE mode in a mobilecommunication network. In step 1202, the UE determines a set ofresources allocated to the UE. The set of resources belongs to a narrowsubband in a wider channel bandwidth. The narrow subband comprises aplurality of contiguous PRB pairs including a control channel and a datachannel. In step 1203, the UE obtains the control channel configurationinformation. The control channel occupies over one or more subframeswithin the set of resources. The control channel configurationinformation comprises a number of aggregation level, a number ofrepetition, and a number of blind decoding trials. In one example, theUE is assigned a measurement gap for intra-frequency and referencesignal time difference (RSTD) measurements. In another example, theBR-UE is configured with frequency hopping and receives PRB pairstarting index per subframe for channel state information (CSI)measurements.

FIG. 13 is a flow chart of a method of intra-frequency and RSTDmeasurements from eNB perspective in accordance with one novel aspect.In step 1301, a base station allocates a first set of resources to a UEin a mobile communication network. The first set of resources belongs toa first narrowband in a wider channel bandwidth. The first narrowbandcomprises a plurality of contiguous PRB pairs over a first period. Instep 1302, the base station allocates a second set of resources to theUE. The second set of resources belongs to a second narrowbandcomprising a plurality of contiguous PRB pairs over a second period. Instep 1303, the base station assigns a measurement gap between the firstand the second periods for intra-frequency and RSTD measurements for theUE. In one example, the base station configures a frequency-hoppingpattern for the UE and indicates PRB pair starting index per subframefor CSI measurements.

FIG. 14 is a flow chart of a method of intra-frequency and RSTDmeasurements from UE perspective in accordance with one novel aspect. Instep 1401, a UE obtains a first set of resources in a mobilecommunication network. The first set of resources belongs to a firstnarrowband in a wider channel bandwidth. The first narrowband comprisesa plurality of contiguous PRB pairs over a first period. In step 1402,the UE obtains a second set of resources belongs to a second narrowbandcomprising a plurality of contiguous PRB pairs over a second period. Instep 1403, the UE performs intra-frequency and RSTD measurements basedon an assigned measurement gap between the first and the second periods.In one example, the UE is configured with frequency hopping and receivesPRB pair starting index per subframe for channel state information (CSI)measurements.

Although the present invention has been described in connection withcertain specific embodiments for instructional purposes, the presentinvention is not limited thereto. Accordingly, various modifications,adaptations, and combinations of various features of the describedembodiments can be practiced without departing from the scope of theinvention as set forth in the claims.

What is claimed is:
 1. A method comprising: allocating a set ofresources to a user equipment (UE) by a base station in a mobilecommunication network, wherein the set of resource belongs to a narrowsub-band in a wider channel bandwidth, and wherein the narrow sub-bandcomprises a plurality of contiguous physical resource blocks (PRBs)including a control channel and a data channel for the UE; and providingthe control channel configuration information to the UE, wherein thecontrol channel occupies over one or more subframes within the set ofresources, and wherein the control channel configuration informationcomprises a number of aggregation level, a number of repetition, and anumber of blind decoding trials.
 2. The method of claim 1, wherein theset of resources is identified by a starting PRB index and a number ofconsecutive PRB pairs, the set of resources is determined based on atleast one of a predefined rule, a random access response, a downlinkcontrol channel information (DCI) order, and higher layer signaling. 3.The method of claim 1, wherein the control channel configurationinformation is determined based on at least one of a predefined rule andhigher layer signaling.
 4. The method of claim 1, wherein the controlchannel configuration information is associated with a mode of the UEconfigured by the base station.
 5. The method of claim 1, wherein thebase station requests the UE to skip specific subframes for decoding thecontrol channel.
 6. The method of claim 1, wherein the control channelcarries downlink control information (DCI) for the data channel, andwherein the DCI comprises a repetition level and a starting subframeindex of the data channel.
 7. The method of claim 1, wherein the basestation assigns a measurement gap for intra-frequency measurement andreference signal time difference (RSTD) measurement.
 8. The method ofclaim 1, wherein the base station configures frequency hopping for theUE and indicates PRB pair starting index per subframe for channel stateinformation (CSI) measurements.
 9. A method comprising: determining aset of resources allocated to a user equipment (UE) in a mobilecommunication network, wherein the set of resource belongs to a narrowsub-band in a wider channel bandwidth, and wherein the narrow sub-bandcomprises a plurality of contiguous physical resource blocks (PRBs)including a control channel and a data channel for the UE; and obtainingthe control channel configuration information, wherein the controlchannel occupies over one or more subframes within the set of resources,and wherein the control channel configuration information comprises anumber of aggregation level, a number of repetition, and a number ofblind decoding trials.
 10. The method of claim 9, wherein the set ofresources is identified by a starting PRB index and a number ofconsecutive PRB pairs, the set of resources is determined based on atleast one of a predefined rule, a random access response, a downlinkcontrol channel information (DCI) order, and higher layer signaling. 11.The method of claim 9, wherein the control channel configurationinformation is obtained based on at least one of a predefined rule andhigher layer signaling.
 12. The method of claim 9, wherein the UE isrequested to skip specific subframes for decoding the control channel.13. The method of claim 9, wherein the control channel carries downlinkcontrol information (DCI) for the data channel, and wherein the DCIcomprises a repetition level and a starting subframe index of the datachannel.
 14. The method of claim 9, wherein the UE is assigned ameasurement gap for intra-frequency measurement and reference signaltime difference (RSTD) measurement.
 15. The method of claim 9, whereinthe UE is configured with frequency hopping and receives PRB pairstarting index per subframe for channel state information (CSI)measurements.
 16. A user equipment (UE), comprising: a resourceconfiguration circuit that obtains a set of resources allocated to theUE in a mobile communication network, wherein the set of resourcebelongs to a narrow sub-band in a wider channel bandwidth, and whereinthe narrow sub-band comprises a plurality of contiguous physicalresource blocks (PRBs) including a control channel and a data channelfor the UE; and a decoder that decodes the control channel configurationinformation, wherein the control channel occupies over one or moresubframes within the set of resources, and wherein the control channelconfiguration information comprises a number of aggregation level, anumber of repetition, and a number of blind decoding trials.
 17. The UEof claim 16, wherein the set of resources is identified by a startingPRB index and a number of consecutive PRB pairs, the set of resources isdetermined based on at least one of a predefined rule, a random accessresponse, a downlink control channel information (DCI) order, and higherlayer signaling.
 18. The UE of claim 16, wherein the control channelconfiguration information is obtained based on at least one of apredefined rule and higher layer signaling.
 19. The UE of claim 16,wherein the UE is requested to skip specific subframes for decoding thecontrol channel.
 20. The UE of claim 16, wherein the control channelcarries downlink control information (DCI) for the data channel, andwherein the DCI comprises a repetition level and a starting subframeindex of the data channel.
 21. The UE of claim 16, wherein the UE is alow cost machine type communication (MTC) device with bandwidthreduction.